The anti-racism campaigner Doreen Lawrence has questioned the apparent focus on non-white people in operations being carried out in and around train stations as part of a government crackdown on illegal immigration.

The mother of the murdered teenager Stephen Lawrence asked why the authorities appeared to be concentrating on non-white people in the stop-and-check operations.

"I'm sure there's illegal immigrants from all countries, but why would you focus that on people of colour, and I think racial profiling is coming into it," she told ITV1's Daybreak programme on Friday.

Asked if the spot checks were a cause for her to take up in her new role in the House of Lords, she replied: "Definitely so."

Lawrence said that stop-and-search had always been at the forefront of her mind, and she has campaigned on the issue for years.

Her seat in the Lords as a Labour peer comes after a 20-year fight for justice for her son, who was stabbed to death at the age of 18 in a racist attack in south London.

The Home Office has denied suggestions that the stop-and-search operations at transport links represent any change or ramping up of policy, saying all the actions have so far been intelligence-led.

The controversy comes as it was revealed that dozens people have been arrested in raids aimed at tackling people working illegally in the UK.

Immigration enforcement officers have arrested 139 suspected immigration offenders at locations including London, Durham, Manchester, Wales and Somerset. Those found to have no right to be in the UK face being deported.

On Friday, the Equality and Human Rights Commission said it would raise both the immigration raids and the van campaign with the Home Office.

"The commission is writing today to the Home Office about these reported operations, confirming that it will be examining the powers used and the justification for them, in order to assess whether unlawful discrimination took place," said a spokeswoman for the equality watchdog.

"The letter will also ask questions about the extent to which the Home Office complied with its public sector equality duty when planning the recent advertising campaign targeted at illegal migration."

On Tuesday commuters at Kensal Green station in west London voiced their serious disapproval after finding UK Border Agency (UKBA) officers at their station stopping tube users to enquire about their immigration status.

Matthew Kelcher, 33, a prospective Labour candidate for the local council, said he was travelling to work when he noticed four uniformed UKBA officers waiting outside the station.

Phil O'Shea, a local resident, gave a similar account to his local paper and said he was threatened with arrest by the officials.

Under the law, immigration officials have no powers of arrest for non-immigration matters.

O'Shea told the Brent & Kilburn Times: "I thought the behaviour of the immigration officers was heavy-handed and frightening. They appeared to be stopping and questioning every non-white person, many of whom were clearly ordinary Kensal Green residents going to work. When I queried what was going on I was threatened with arrest for obstruction and was told to 'crack on'."

The Unite union has confirmed that it is still seeking legal advice on whether the Home Office "incited racial hatred" by permitting vans to travel around London with the message "go home or face arrest".

Solicitors acting for residents in east London who were disturbed by the sight of the Home Office-sponsored vans have written to the department to say they will go to the courts to have the campaign declared unlawful through judicial review.

A Home Office spokesman defended the tactics: "We make no apology for enforcing our immigration laws and our officers carry out hundreds of operations like this every year around London. Where we find people who are in the UK illegally, we will seek to remove them.

"Immigration enforcement officers conducted an operation at Walthamstow Central underground station and hub today, based on intelligence, where they questioned individuals to check if they had the right to be in the UK. They arrested 12 people who were in the country illegally. Two further people were arrested in follow-up house searches."

The shadow immigration minister, Chris Bryant, said: "The home secretary said that it is unacceptable to stop someone simply on the basis of their ethnicity. Theresa May said that someone from an ethnic [minority] background was seven times more likely to be stopped than a white person, and she said that this was wrong and we supported her."

Bryant called on May to reassure the public that people were not being targeted because of their ethnicity.

"With enforcement operations now under the direct control of the Home Office, she must establish straight away whether the rules preventing racial profiling are being enforced," he said.

He added: "Intelligence-led operations to remove illegal immigrants are to be welcomed. Racial profiling is not."

On the streets of Walthamstow, London, where the UK Border Agency carried out spot checks for illegal migrants and made arrests in a clampdown last week, there was a growing tide of resentment, anger and incredulity at the targeting of skin colour